While Darrow compels Crosley to help identify the Soviet spy on the hill, the other residents of Los Alamos race to make a place in history as the scheduled nuclear explosion is just days away.

To witness history and how it changes everything the residents knew till now regarding the Manhattan Project, CLICK HERE.

According to Rotten Tomatoes, a new era is ushered in with the first test of an atomic weapon.

In the previous episode, titled "Brooklyn", Abby's investigation into the circumstances of Jean Matlock's death led to a shocking movement of reckoning for the Isaacs family.

Darrow tapped Crosley to help identify the Soviet spy on the Hill, forcing him to choose sides. Crosley had no choice but to go with Bueker and question the Handler.

Nora tried to change the mission but Meeks' conscience kicked in and he decided to improvise. He met with his fellow Soviet spy who ended up being Stan.

Franks ascended to a leadership role in Little Boy, but his primary concern wasn't the delivery of the bomb, it was helping Liza.

Liza presented the Army with a comprehensive overview of the medical and environmental implications of the test they were about to perform, but discovered once and for all that politics trump science during wartime.

Crosley realised Meeks is the spy. Helen told Darrow that Frank was the reason the pretest failed.

Earlier, when a crucial dry run failed just weeks before the Trinity test, Charlie and Frank were forced to work together, setting aside old wounds for the good of the project.

Frank made certain the test would fail to get him back into the project. Abby was forced to face truths about Charlie's past when Charlie's father contacted her.

Crosley and Hogarth's spy story culminated when they departed the Hill with a cache of stolen documents, only to be captured and returned to Darrow, who had a surprise in store for Hogarth.

Meeks received new orders from Nora, along with a new understanding of his role in the mission. Liza continued studying the potential health effects of the test and received surprising help from Fritz.

Helen's romance with Stan, the patent lawyer, deepened, leading to a surprising new prospect for her future.